Valentia Coast Guard is concerned for the well-being of two Dutch men who have been missing in County Cork since Saturday.
Coast Guard, Garda and RNLI units are searching the sea and shoreline around the Sheep's Head peninsula, while the Coast Guard helicopter is supporting their efforts.
The two men are understood to have been staying at a house near Sheep's Head.
The last contact with the men was made at 1.30pm on Saturday afternoon, when one of the men called his mother to tell her they were planning to walk to the lighthouse in bad weather.
Gardaí have been unable to contact the men and are now trying to trace one of their mobile phones which is ringing out.